Application Working Path

System.Reflection.Assembly.GetExecutingAssembly.Location will return the full path and the name of the executing assembly.

Edit
And the easiet one is System.AppDomain.CurrentDomain.BaseDirectory()

But, how can I set the working directory of the application that I launch?
Oh, I misread your first post. You need to StartInfo to set the Working Directory like this Process pTemp = new Process();
pTemp.StartInfo.WorkingDirectory = @"C:\Temp";
pTemp.StartInfo.FileName = "notepad.exe";
pTemp.Start();

Thank you!
You are welcome :)